Powder Pattern Program An interactive Fortran IV program has been written t o aid in the characterization of crystalline materials by calculating and plotting the theoretical positions ofthe Braggrefleetions as a function of 20. The program is capable of calculating and dotting Bragg reflections for anv crvstalline substance and is intended to aid in the comoarison of isomorohous materials as well a s in %e characterization bf new substances. Provisions have been made to account 'for svstematie a b s k e s associated uwh any sparegnrup. l'hr dntn nrrerwry i